Class FileCleaningTracker

Keeps track of files awaiting deletion, and deletes them when an associated
marker object is reclaimed by the garbage collector.

This utility creates a background thread to handle file deletion.
Each file to be deleted is registered with a handler object.
When the handler object is garbage collected, the file is deleted.

In an environment with multiple class loaders (a servlet container, for
example), you should consider stopping the background thread if it is no
longer needed. This is done by invoking the method
exitWhenFinished, typically in
ServletContextListener or similar.

getDeleteFailures

exitWhenFinished

Call this method to cause the file cleaner thread to terminate when
there are no more objects being tracked for deletion.

In a simple environment, you don't need this method as the file cleaner
thread will simply exit when the JVM exits. In a more complex environment,
with multiple class loaders (such as an application server), you should be
aware that the file cleaner thread will continue running even if the class
loader it was started from terminates. This can consitute a memory leak.

For example, suppose that you have developed a web application, which
contains the commons-io jar file in your WEB-INF/lib directory. In other
words, the FileCleaner class is loaded through the class loader of your
web application. If the web application is terminated, but the servlet
container is still running, then the file cleaner thread will still exist,
posing a memory leak.

This method allows the thread to be terminated. Simply call this method
in the resource cleanup code, such as
ServletContextListener.
Once called, no new objects can be tracked by the file cleaner.